Now that you’ve had a chance to make your own predictions about how the Dry Valleys will respond to a warmer world, I want to take you through one of the predictions our lead scientists have made. I’ll also describe a big experiment that we just started to simulate the impacts of the warming climate on the Dry Valley ecosystem.
In the Dry Valleys, liquid water is precious. It determines where life can exist and it links glaciers, streams, soils, and lakes. As it flows across the landscape, it brings with it life and nutrients. With absolutely no liquid water coming out of the sky (all precipitation here falls as snow), melting ice and snow provide all the liquid water in the valleys. So what happens when it warms? Higher temperatures will lead to more melting, and more melting means more liquid water flowing across the landscape.
It’s easy to visualize glaciers and snow melting, but it’s harder to imagine the melting that will happen out of sight beneath our feet. Permafrost, or permanently frozen soil, hidden only tens of centimeters below the ground, will also respond to a warming climate. In the Arctic, thawing permafrost has already started causing problems – imagine roads and buildings, built on solid frozen ground, suddenly becoming unstable as the ground thaws beneath them. Will something similar happen in the Dry Valleys? What will permafrost thaw mean for life in the Dry Valleys? How will the additional liquid water change the ecosystem?
That’s what the lead scientists were wondering when they designed the Pulse Press Project, meant to simulate permafrost melt along a hill slope. The basic idea behind the project is to add liquid water at the top of the hill, and to watch what happens as the water flows downhill. Because permafrost melt happens below the ground surface, the liquid water gets added to trenches so that the water flows through the soil rather than over the soil. The project is a long-term study, meaning that water will get added over the course of many years. Each year, the team will collect soil samples to see how the chemistry, soil moisture, and nematode abundance change as we add more liquid water.
All of this sounds good in theory, but how do you actually do this in the field? Well, you need a huge tank, a water pump, some tubes, and a huge amount of patience. The hill slope is conveniently located near a pond, so the first step is to pump that water uphill into a holding tank. The water then gets slowly released into trenches, and then we wait for the water to seep down the slope.
And wait. And wait some more. Apparently it takes a long time for water to flow downhill through the soil.
Although it felt like it was taking a long time, by the end of two days, all the water has been successfully applied! Now we wait until next year, when we’ll collect more soil samples and apply more water.
So, what do you think will happen to the hill slope? Will the abundance of nematodes change? Will the chemistry of the soil change? Will the hill change visibly, or will all the changes be hidden from the naked eye? Even the lead scientists don’t know the answers to these questions. And that’s what makes field research so exciting. We can make as many educated guesses as we like, but we can always be surprised by what actually happens.